Salinity distribution is related to evaporation-precipitation
cycle variations at different latitudes. When seawater freezes, salinity
increases in the remaining water. Regional variations in salinity exist
also.

Salinity is generally higher in the sub-tropical latitudes
that are remote from land.

Salinity is generally lower at the equator, in polar
and sub-polar regions, and near continents.

Sea-level Height

Eustatic sea level changes are caused by changes of
volume of ocean water as a result of extensive formation or melting of
icecaps and glaciers.

Eustatic changes of sea level take place simultaneously
and uniformly throughout the world. Eustatic equilibrium (balance) is
easily and quickly attainable.

Human civilization has emerged during a long period
of relatively stable sea level.

The predicted greenhouse warming of the planet could
cause higher-than-average global temperatures, which, in turn, would cause
the current polar ice sheets and glaciers to melt and sea level to rise.

Seafloor Topography

Tectonic processes (such as subduction and seafloor
spreading) and sedimentation are the principal agents that shape and change
the seafloor topography over time. Changes in climate can also affect
it.